PRODUCTION TECHNOLOGIES UNCONVENTIONAL

LEARNING OUTCOMES OF THE COURSE UNIT

On completion of the course, students should have attained knowledge and expertise relating to non-conventional manufacturing technologies, including laser materials processing, additive manufacturing, ultrasonic machining, water jet machining, abrasive water jet machining, electro-discharge machining and electro-chemical machining. Study of these processes will be undertaken with a systematic approach based on modelling, to allow interpretation and understanding of the laws and mechanisms on which they are based. The advantages and limitations of each process will be analysed both in comparison to traditional machining technologies as well as for production of specific components. Process modelling will be oriented towards the analysis and prediction of the influence of process parameters on the obtained results.

ASSESSMENT METHODS AND CRITERIA

1) A report summarising the results of a project relating to a specific non-conventional manufacturing technology. The report will be assessed on a scale of 0-30 (weighted 50% of final course mark);

2) An oral exam consisting of questions relating to two different non-conventional manufacturing technologies covered in the course. The oral exam will be assessed on a scale of 0-30 (weighted 50% of final course mark).

Students should note that on line registration is obligatory for the oral exam. Exam results will be published on the Esse3 portal within one week of the exam date.

TEACHING METHODS

Lessons with comprise both theoretical treatment of various non-conventional manufacturing technologies, as well as analysis of specific cases where such technologies have been successfully introduced into manufacturing environments. Presentation slides used as supporting material during lessons will be uploaded to the Elly platform on a weekly basis. Course registration on line is necessary to download the slides. Practical exercises will be undertaken for select manufacturing technologies to provide a more thorough understanding of the physical phenomena addressed during lessons. The preparation of a project relating to a specific non-conventional technology will form a fundamental part of the learning process and will be discussed during the oral exam.

Snell’s law. The Fresnel equations and differences in absorption of “p” and “s” polarised waves. Laser-materials interactions: differences between metallic and non-metallic materials. Reflectivity and absorptivity and the dependence of these parameters on the wavelength, temperature, surface roughness, presence of oxide layers etc. Propagation and optical absorption within materials according to the Beer-Lambert law. Thermal effects on materials and changes of state in conditions of thermal equilibrium. Classification of the main processes as functions of process parameters.

Solutions for the linear heat flux equation for semi-infinite solids subject to laser heating. Start-up and switch-off of laser source and effects on the treated material. Laser hardening of large surfaces and axial-symmetric components. Numerical simulation of general cases.

Laser welding in different geometric configurations (overlap, but welding etc.). The influence of process parameters on the transition from conduction to keyhole welding. Instability of the keyhole. Modelling of laser welding: moving linear and point heat sources. Pulsed laser welding of thin sections.

Pulsed laser process, including laser ablation and surface modification. Laser-material interactions as a function of the pulse duration and fluence. Relaxation time and thermal conduction following ultrashort laser pulses. Changes of state in non-equilibrium conditions: over heating, critical temperature, vaporisation, fragmentation, phase explosion. Numerical simulation of laser ablation with short and ultrashort pulses. Industrial applications and systems for short pulse laser processing.